:root{--ink:#203f43;--muted:#657d7b;--paper:#f6f5ef;--line:#d9e3dd;--teal:#176c62;--mint:#d9f0e3;--amber:#eeb45a;--rose:#b25266;--shadow:0 10px 32px #25463c09}*{box-sizing:border-box}[hidden]{display:none!important}body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.65 system-ui,-apple-system,'Segoe UI',sans-serif}body:before{content:'';position:fixed;inset:0;pointer-events:none;background-image:radial-gradient(#8aab971e 1px,transparent 1px);background-size:22px 22px;z-index:-1}main{max-width:1000px;margin:auto;padding:34px 24px}header{margin-bottom:28px}.brand{font-size:12px;letter-spacing:2.5px;font-weight:800;display:flex;gap:20px;align-items:center}.brand span{color:var(--muted);letter-spacing:1px;font-weight:500}.headerline{display:flex;justify-content:space-between;align-items:center;gap:14px}h1{font-size:clamp(28px,4vw,42px);letter-spacing:-1.2px;margin:12px 0 4px;line-height:1.3}h2{font-size:23px;margin:6px 0 12px;line-height:1.4}.lead{color:var(--muted);margin:8px 0}.tools{display:flex;gap:8px;flex-shrink:0}.panel{background:#fffefa;border:1px solid var(--line);border-radius:22px;padding:28px;margin:20px 0;box-shadow:var(--shadow)}.eyebrow{font-size:12px;letter-spacing:1.6px;font-weight:800;color:var(--teal)}.intro{border-top:5px solid var(--teal)}.intro-layout{display:grid;grid-template-columns:1fr 170px;gap:35px;align-items:center}.intro h2{font-size:29px;max-width:600px;margin-top:12px}.intro p{color:var(--muted)}#rules{padding:12px 15px;background:#f0f4ed;border-radius:10px;color:var(--ink);font-size:15px}button,input,select{font:inherit}button{border:1px solid transparent;border-radius:11px;padding:11px 19px;background:var(--teal);color:white;cursor:pointer;font-weight:700;transition:background .15s,transform .15s}button:hover:enabled{filter:brightness(1.08);transform:translateY(-1px)}button:disabled{opacity:.48;cursor:default}.quiet{background:#edf3ec;color:var(--ink);border-color:#dce6db;font-size:14px}.primary{box-shadow:0 4px 0 #124d47;padding:13px 25px}.primary:active:enabled{transform:translateY(2px);box-shadow:0 2px 0 #124d47}button:focus-visible,input:focus-visible,select:focus-visible{outline:3px solid var(--amber);outline-offset:3px}input,select{border:1px solid #bccfc3;background:#fff;border-radius:10px;padding:10px 13px;color:var(--ink)}#nameLabel{display:inline-flex;gap:12px;align-items:center;margin:12px 16px 12px 0}#player{max-width:220px}#introStatus{margin-bottom:0;font-size:15px}.robot{width:146px;height:168px;position:relative;transform:rotate(5deg);justify-self:center}.antenna{height:22px;width:5px;background:#53776b;margin:auto}.antenna:before{content:'';display:block;width:15px;height:15px;border-radius:50%;background:var(--amber);transform:translate(-5px,-7px)}.face{height:65px;background:#c5e1d5;border:3px solid #2e685c;border-radius:18px;display:flex;gap:29px;align-items:center;justify-content:center;position:relative;box-shadow:5px 6px 0 #a9c7b5}.face i{height:14px;width:13px;border-radius:5px;background:#244f48}.face b{position:absolute;width:25px;height:6px;background:#548d79;bottom:12px;border-radius:4px}.robotbody{margin:9px auto;width:100px;text-align:center;border:3px solid #2e685c;border-radius:14px;background:var(--amber);font-size:23px;font-weight:800;padding:6px}.feet{width:100px;height:12px;margin:auto;border-left:27px solid #466e60;border-right:27px solid #466e60}.statusbar{display:flex;justify-content:space-between;gap:12px;font-size:15px;font-weight:700;padding:0 8px}.workshop{padding:26px 28px}.sectionline{display:flex;align-items:center;justify-content:space-between;gap:12px}.badge{font-size:13px;border-radius:7px;padding:3px 10px;background:#e7efe6;color:var(--teal)}#levelTitle{margin-top:12px}.instruction{margin:0;color:var(--muted);font-size:15px}.equation{text-align:center;font-weight:750;font-size:clamp(23px,4vw,35px);padding:22px 3px;overflow-wrap:anywhere;line-height:1.5}.equals{color:#80948a}#output{color:var(--teal)}.scene{position:relative;border-radius:16px;border:1px solid #d0ded3;background:#edf3ec;overflow:hidden;min-height:240px}.scene-head{display:flex;justify-content:space-between;font-size:11px;letter-spacing:2px;font-weight:800;color:#6e8d7c;padding:11px 18px;border-bottom:1px solid #d9e3d7}.pilot{color:var(--teal)}.source{min-height:153px;padding:28px 20px;display:flex;justify-content:center;align-items:center;gap:12px;flex-wrap:wrap}.term{border:2px solid #2e7b70;border-radius:10px;background:#c9e6de;padding:13px 19px;font-size:25px;font-weight:750;box-shadow:0 4px 0 #a9c7bd}.term.constant{background:#ffe4ad;border-color:#b58b44;box-shadow:0 4px 0 #e8ce99}.term.negative{background:#f3dfe4;border-color:#b66a7b;box-shadow:0 4px 0 #dec3ca}.bundle{border:2px dashed #71968a;border-radius:13px;padding:16px 12px;display:flex;gap:9px;align-items:center;background:#fff9}.bundle .term{font-size:21px;padding:8px 12px}.factor{font-weight:800;color:#486f60;font-size:25px}.lanes{padding:15px 16px 6px}.lane{display:grid;grid-template-columns:70px 1fr;border-bottom:1px dashed #c7d6c9;min-height:74px;padding:8px 0;gap:12px}.lane-label{font-size:13px;color:#4d7360;align-self:center}.cards{display:flex;flex-wrap:wrap;align-content:center;align-items:center;gap:7px;min-height:48px}.tile{display:inline-flex;position:relative;align-items:center;justify-content:center;width:46px;height:38px;border:2px solid #2e7b70;border-radius:6px;background:#c9e6de;box-shadow:0 3px 0 #afcfc0;font:700 16px/1 system-ui;transition:transform .4s,opacity .4s,background .3s}.tile.constant{width:36px;height:36px;background:#ffe4ad;border-color:#b58b44;box-shadow:0 3px 0 #e8ce99}.tile.negative{background:#f3dfe4;border-color:#b66a7b;box-shadow:0 3px 0 #dec3ca}.tile.pairing{outline:3px solid #e4ad44;background:#fff2c7;transform:translateY(-6px)}.tile.removed{opacity:.15;transform:scale(.65);box-shadow:none;text-decoration:line-through}.zero-bin{display:flex;align-items:center;justify-content:flex-end;gap:12px;color:#637c6c;font-size:12px;margin-top:8px}.zero-bin b{border:1px dashed #9ab39f;padding:1px 14px;border-radius:7px}#pairLine{text-align:center;min-height:26px;font-size:14px;font-weight:700;color:#6b5b36}.readout{background:#254c43;color:#e5f3de;text-align:center;min-height:49px;padding:8px;font:700 22px/1.5 ui-monospace,monospace;border-top:3px solid #d3dfd0}.choices{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:22px}.choice{background:#fff;color:var(--ink);border:1px solid #cbdad0;padding:14px;text-align:left;font-size:20px;display:flex;align-items:center;gap:15px}.choice span{font-size:12px;font-weight:800;color:#748b7f;display:inline-grid;place-items:center;width:25px;height:25px;background:#edf3ec;border-radius:6px}.choice.selected{border:2px solid var(--teal);background:#e8f4ed}.choice.correct{background:#e1f0e5;border-color:#407f5e}.choice.wrong{background:#f7e8e7;border-color:#be7e82}#feedback{min-height:30px;font-size:15px;color:var(--muted);margin:16px 0 10px}.proof{background:#f7f6ee;border-left:3px solid var(--amber);border-radius:0 10px 10px 0;padding:12px 18px;margin:14px 0;font-size:15px}.proof ol{padding-left:25px;margin:0}.proof li{padding:3px 0;overflow-wrap:anywhere}.proof li:last-child{font-weight:750}#reason{margin:8px 0 0;color:#63766c}.actions{display:flex;justify-content:center;gap:12px;flex-wrap:wrap;margin-top:16px}#assembly{border-top:1px solid var(--line);margin-top:24px;text-align:center;padding-top:18px}.assembly-caption{font-size:15px;color:var(--teal);font-weight:750}#machine{display:block;width:100%;height:auto;max-height:240px;margin:auto;background:#eef3e9;border-radius:12px}#machine .part{transform-box:fill-box;transform-origin:center;transition:transform 1.1s cubic-bezier(.25,.7,.3,1),opacity .5s}#machine .running{animation:gearspin 4s linear infinite;transform-box:fill-box;transform-origin:center}#machine .reverse{animation-direction:reverse}#machine .piston{animation:piston 1.2s ease-in-out infinite alternate;transform-box:fill-box}#machine .piston:nth-child(2){animation-delay:.4s}#machine .piston:nth-child(3){animation-delay:.8s}@keyframes gearspin{to{transform:rotate(360deg)}}@keyframes piston{to{transform:translateY(-22px)}}.collection h2{font-size:19px}.collectionCount,#collectionCount{font-size:13px;color:var(--muted)}.gallery{display:grid;grid-template-columns:repeat(6,1fr);gap:10px;margin-top:15px}.gallery-item{background:#f0f2eb;border:1px dashed #ced8cc;border-radius:10px;min-height:88px;display:flex;align-items:center;justify-content:center;flex-direction:column;gap:5px;color:#879889;font-size:11px;text-align:center;padding:7px}.gallery-item b{font-size:23px;opacity:.5}.gallery-item.built{border-style:solid;border-color:#9fbeab;background:#e4f0e2;color:var(--teal)}.gallery-item.built b{opacity:1}.save-row{display:flex;align-items:center;gap:14px;flex-wrap:wrap;border-top:1px solid var(--line);padding:16px 0}.save-row span:last-child{font-size:14px;color:var(--muted)}.tablewrap{overflow:auto}table{width:100%;border-collapse:collapse;min-width:550px;font-size:14px}th,td{text-align:left;padding:12px 9px;border-bottom:1px solid var(--line)}th{font-weight:600;color:var(--muted);font-size:12px}.pagination{display:flex;justify-content:center;align-items:center;gap:18px;font-size:14px}#boardStatus{font-size:14px;color:var(--muted)}.model-note,footer{text-align:center;color:var(--muted);font-size:12px;margin:18px 0}a{color:var(--teal)}footer a{text-decoration:none}.animate-in{animation:arrive .65s ease both}@keyframes arrive{from{opacity:0;transform:translateY(-20px)}to{opacity:1;transform:translateY(0)}}@media(max-width:640px){main{padding:20px 12px}.headerline{display:block}.tools{margin-top:14px}.panel{padding:20px 16px;border-radius:17px}.intro-layout{grid-template-columns:1fr}.robot{display:none}.intro h2{font-size:25px}#nameLabel{display:flex;flex-wrap:wrap}.choices{grid-template-columns:1fr;gap:8px}.choice{padding:10px 14px}.gallery{grid-template-columns:repeat(3,1fr)}.lane{grid-template-columns:72px 1fr;gap:6px}.lane-label{font-size:12px;line-height:1.4;overflow-wrap:anywhere}.lanes{padding:10px}.tile{width:39px;height:35px}.tile.constant{width:31px;height:31px}.cards{gap:6px}.statusbar{font-size:13px;flex-wrap:wrap}.source{padding:20px 10px}.term{font-size:20px;padding:10px 12px}.bundle{padding:12px 8px;gap:6px}.bundle .term{font-size:18px;padding:7px}.equation{font-size:23px}.sectionline{flex-wrap:wrap}.model-note{text-align:left}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
.gallery-item svg{width:100%;height:52px}.source .bundle small{font-size:11px;writing-mode:vertical-rl;color:#5a7c6a}
.medal{display:inline-grid;place-items:center;width:27px;height:27px;border-radius:50%;border:2px solid;font-weight:800;box-shadow:0 2px 0 #25463c15}.medal-1{background:#f9dc88;border-color:#c59734;color:#77500e}.medal-2{background:#e2e7e9;border-color:#9ba9ae;color:#52636a}.medal-3{background:#e9c3a8;border-color:#b58460;color:#784f31}